Influence of vasoactive drugs on the intratumor distribution of blood flow and vascular volume in a transplantable rat fibrosarcoma.

The intratumor distribution of plasma volume and of blood flow was studied simultaneously by radioisotope techniques in a transplantable rat fibrosarcoma. Intravenous administration of norepinephrine changed the distribution of both plasma volume and blood flow to produce low values in tumor and in normal muscle. Intravenous administration of papaverine was surprisingly followed by similar effects, probably due to a direct influence of papaverine on cardiac function. Intraaortal administration of papaverine into the studied tissue area did not influence tumor blood flow or plasma volume but increased normal muscle plasma volume. The results might support a previously suggested possibility that one can directly influence the tumor vascular bed with vasoconstricting drugs, while tumor vessels are more resistant to pharmacologic dilatation probably because of their normal state of close to maximal dilatation.